Pumped-Storage Hydropower

Think of two tanks at different heights joined by a pipe. Water moves between them to store and release power.

1. What is pumped-storage hydropower (PSH or PSP)?

The US Department of Energy calls pumped-storage hydropower a proven energy storage technology. A plant has an upper reservoir and a lower reservoir. Water conveyances such as penstocks and tunnels join them.

Indian official papers use PSP for “pumped storage project”. The Ministry of Power says PSPs provide long-duration energy storage and balancing power.

• An upper reservoir and a lower reservoir.
• Water moves between them through tunnels and a powerhouse.

2. What happens in pumping mode and generating mode?

A plant has two modes. In pumping mode it charges. In generating mode it discharges.

The DOE says water is pumped from the lower to the upper reservoir when net demand is low. It is also pumped when supply is higher than demand. To generate power, water is released to a powerhouse that holds the pump-turbines and motor-generators. The water spins a turbine near the lower reservoir. The turbine drives a generator.

The DOE says most plants use reversible pump-turbines. Some designs use separate pumps and turbines.

• Pumping (charging): lower reservoir to upper reservoir.
• Generating (discharging): upper reservoir to lower reservoir, through the turbine.
• Reversible unit: one machine does both jobs.

3. What is round-trip efficiency, and what is it for PSH?

Round-trip efficiency is how much energy a plant returns. The DOE gives around 80% for new plants.

The DOE says the typical round-trip efficiency of new PSH plants is currently around 80%. So about 80 units come back for every 100 units used to pump. Its cost table for a 100 MW plant with 10 hours of storage uses 80% and a 60-year project life.

The DOE says ternary and quaternary plants, running in hydraulic short-circuit mode, have practically a full operating range, from -100% to 100% of capacity.

4. What is the difference between open-loop and closed-loop PSH?

The DOE says open-loop systems are continuously connected to a naturally flowing body of water. Closed-loop systems are not.

The DOE says closed-loop plants typically have fewer environmental impacts. They also face a shorter licensing timeline in the US. The DOE gives 2 years, under an expedited FERC route for closed-loop projects at abandoned mine sites. Open-loop plants are typically cheaper because only one reservoir is built. But they face more environmental hurdles.

• Open-loop: linked to a naturally flowing body of water.
• Closed-loop: not continuously connected to a naturally flowing body of water.

5. How does India's Central Electricity Authority (CEA) classify plants as on-stream or off-stream?

The CEA status sheet splits PSPs into “on stream” and “off stream”. On-stream plants are labelled ‘Generating PSPs’ and off-stream plants ‘Storage PSPs’ on the CEA sheet.

The CEA then marks off-stream plants as “open loop” or “closed loop”. The PIB (July 2026) says closed-loop off-stream schemes are exempt from CEA concurrence.

The sheet lists state, district, units, MW, developer and commissioning dates.

Solar and wind output is intermittent (PIB). Storage helps.

6. Why does a grid with more solar and wind need storage?

The PIB (17 Nov 2025) quotes Power Minister Manohar Lal. PSPs can store surplus green power. They can then meet demand in non-solar hours.

The PIB (July 2026) says PSPs support renewable integration. They store surplus energy off-peak and supply power at peak demand.

The PIB (9 Mar 2026) says the transmission system is planned to integrate over 500 GW of non-fossil capacity by 2030. It says the Government promotes storage and hybrid solutions to address intermittency.

7. What grid services does a PSP provide beyond storing energy?

The PIB (July 2026) names balancing power and ancillary services. These include frequency regulation, voltage support and black start capability.

The PIB (Sep 2024) says the two PSPs it concurred will help meet peak demand in non-solar hours and give “inertia” to the grid.

8. How does PSP compare with battery storage?

The two are planned side by side in India. The PIB (9 Mar 2026) says the National Electricity Plan transmission volume covers 35.6 GW of PSPs up to 2031-32. It also considers about 47 GW of battery energy storage systems (BESS) by 2031-32.

The Government backs batteries with two Viability Gap Funding schemes for about 43.8 GWh of BESS. They were launched in March 2024 and June 2025.

The PIB (Dec 2023) says the levelised cost of storage of PSPs is viable. So there are no plans for Viability Gap Funding for PSPs.

The DOE uses a 60-year life for a PSH plant. The DOE paper models 10 hours of storage. No official source checked gives a like-for-like battery life or cost. So no numeric battery comparison is made here.

9. What is the global PSH capacity, and how fast is it growing?

The International Hydropower Association (IHA) says global pumped storage reached 189 GW in 2024. It says 8.4 GW was added in 2024. Global capacity rose 5%.

The IHA says the global hydropower pipeline now exceeds 1,075 GW. About 600 GW of it is pumped storage and 475 GW is conventional hydropower. The report was released on 25 June 2025.

The DOE gives an older snapshot. It says global PSH capacity was approximately 160 GW in 2020.

10. How much PSH does the United States have?

The DOE (July 2023) says the US has 43 plants with 21.9 GW installed. It says 42 are open-loop and one is a 40 MW closed-loop plant. The earliest US operation was the Rocky River project in Connecticut, commissioned in 1929.

The DOE says that in 2019 this was about 93% of US utility-scale energy storage power capacity. It was about 99% of US energy storage capability.

11. How much PSP capacity does India have in operation?

The CEA status sheets show 10 operating PSPs with 7,425.60 MW. Eight are on-stream with 4,845.60 MW. Two are off-stream with 2,580 MW. The same total appears in the CEA files of 8 May 2026 and 10 Jul 2026.

This is above the PIB (28 Jul 2025) figure of 6.2 GW at 30 June 2025. The CEA sheet gives unit dates after the PIB date. Pinnapuram units run from June to October 2025. Tehri units run from June 2025 to April 2026.

The PIB (17 Nov 2025) says about 224 GW of PSP potential has been identified. The potential figure depends on the source and the date. The PIB gave about 119 GW in June 2023 (see item 18). The CEA survey total in its file of 10 Jul 2026 is 310,104.6 MW. The May sheet showed 290,195.6 MW and the July sheet 310,104.6 MW.

12. Which are India's operating pumped-storage plants?

This is the CEA list of PSPs above 25 MW, as in its file of 10 Jul 2026. States follow the CEA 2026 sheet.

• Kadana: Gujarat, 4×60 = 240 MW, GSECL.
• Sardar Sarovar: Gujarat, 6×200 = 1,200 MW, SSNNL.
• Ghatgar: Maharashtra, 2×125 = 250 MW, MAHAGENCO, commissioned 2008.
• Bhira: Maharashtra, 1×150 = 150 MW, Tata Power, units from 1927 and 1949.
• Tehri: Uttarakhand, 4×250 = 1,000 MW, THDC, units from June 2025 to April 2026.
• Srisailam LBPH: Telangana, 6×150 = 900 MW, TSGENCO, 2001 to 2003.
• Kadamparai: Tamil Nadu, 4×100 = 400 MW, TANGEDCO, 1987 to 1989.
• Nagarjuna Sagar: Telangana, 7 units totalling 705.6 MW, TSGENCO, 1980 to 1985.
• Pinnapuram: Andhra Pradesh, 1,680 MW, Greenko, off-stream closed loop, units from June to October 2025.
• Purulia: West Bengal, 4×225 = 900 MW, WBSEDCL, 2007, off-stream closed loop.

The first eight add to 4,845.6 MW. All ten add to 7,425.6 MW.

The PIB of 23 Dec 2023 listed Srisailam LBPH and Nagarjuna Sagar under Andhra Pradesh. The CEA 2026 sheet shows Telangana.

13. What is special about Pinnapuram and Tehri?

Pinnapuram, in Kurnool district of Andhra Pradesh, is off-stream and closed-loop.

The PIB (17 Nov 2025) says all eight units of the 1,680 MW Pinnapuram PSP were commissioned in 2025-26. It also names the 500 MW Tehri PSP among the 2025-26 commissionings. The CEA lists all four Tehri units, 1,000 MW. The PIB of 23 Dec 2023 gave Pinnapuram as 1,200 MW. Later sources give 1,680 MW, so this lesson uses 1,680 MW. The CEA shows all four Tehri units, 1,000 MW, running by April 2026.

14. Do Kadana and Sardar Sarovar run in pumping mode?

The PIB (23 Dec 2023) says Kadana and Sardar Sarovar RBPH were then not operational in pumping mode.

We found no later official line on this. The 2026 CEA sheet still counts them as operating PSPs.

15. Are Kundah and Panchet Hill operating PSPs?

Kundah is not yet operating as a PSP. The CEA lists Kundah Stages I, II and III, 500 MW, in Tamil Nadu as under construction. The PIB (July 2026) gives its target as Feb 2027.

Panchet Hill does not appear in any CEA PSP list checked. So it is not counted as a PSP.

16. Which pumped-storage projects are under construction?

The PIB (20 Jul 2026) says 11 PSPs with 15,870 MW are under construction. The dates are targets given by the Ministry.

• Upper Sileru, Andhra Pradesh: 1,350 MW, Feb 2029.
• Sharavathy, Karnataka: 2,000 MW, May 2032.
• Kundah, Tamil Nadu: 500 MW, Feb 2027.
• MP30 Gandhi Sagar, Madhya Pradesh: 1,920 MW, Dec 2026.
• Chitravathi, Andhra Pradesh: 500 MW, Feb 2027.
• Bhivpuri, Maharashtra: 1,000 MW, Feb 2029.
• Saundatti, Karnataka: 1,600 MW, Dec 2027.
• Bhavali, Maharashtra: 1,500 MW, Dec 2028.
• Gandikota, Andhra Pradesh: 1,000 MW, Mar 2029.
• Tarali, Maharashtra: 1,500 MW, Jun 2029.
• Saidongar-1 Karjat, Maharashtra: 3,000 MW, Dec 2029.

The PIB (23 Dec 2023) listed Koyna Left Bank, 80 MW, with work stalled. It is not in the 2026 list.

17. Which projects are cleared but not yet under construction?

The PIB (20 Jul 2026) says 6 PSPs with 8,140 MW are concurred or appraised by the CEA. They are yet to be taken up for construction.

• Chichlik, Uttar Pradesh: 1,560 MW, appraised on 8 Jul 2026 (PIB). The CEA sheet gives an authority meeting on 16 Jun 2026.
• Pane, Maharashtra: 1,500 MW.
• Shirawta, Maharashtra: 1,800 MW.
• Kandhaura, Uttar Pradesh: 1,680 MW, 13 Jun 2025.
• Upper Indravati, Odisha: 600 MW, 19 Aug 2024.
• Turga, West Bengal: 1,000 MW, concurred 5 Oct 2016.

The CEA file of 10 Jul 2026 also lists projects under survey and investigation. It shows 66 projects with 93,490 MW. The same file counts 84 PSPs, 118,140 MW, outside operation (94 with the 10 operating plants).

18. How has the pipeline grown over time?

These are dated snapshots from PIB. They count projects at different dates.

• June 2023: identified potential about 119 GW. 8 projects (4.7 GW) operating and 4 (2.8 GW) under construction.
• 30 Jun 2025: 10 PSPs (6.2 GW) commissioned and 8 (8.5 GW) under construction.
• 17 Nov 2025: about 7 GW commissioned and about 12 GW under construction.
• 20 Jul 2026: 11 PSPs (15,870 MW) under construction.

These are not a growth rate. The PIB counts and the CEA counts do not use the same cut-off dates.

19. What did the 2019 and 2023 Government measures do?

In March 2019 the Government approved measures to promote hydropower. These declared large hydro (over 25 MW) a renewable energy source. They also set a Hydro Purchase Obligation and budgetary support for enabling infrastructure.

The Ministry of Power notified Guidelines to promote PSPs on 10 April 2023. The PIB (28 Jul 2025) says they provide ways to allot sites. They also exempt PSPs from free power and Local Area Development Fund obligations. They rationalise environmental clearance and allow use of exhausted coal mines.

The budgetary support guidelines were notified on 28 September 2021.

20. What is the ISTS charge waiver for PSPs?

ISTS means Inter-State Transmission System. The PIB (20 Jul 2026) says CERC’s notification of 26 June 2025 gives a 100% ISTS waiver. It lasts 25 years from the commercial operation date. It applies where construction is awarded on or before 30 June 2028. The PIB of 23 Dec 2023 described a part waiver in steps of 25%. The later notification is used here, as the PIB reports it.

An earlier order was dated 23 Nov 2021. The PIB (8 Dec 2022) says it covered PSPs and BESS commissioned up to 30 June 2025. The period was 25 years for PSPs and 12 years for BESS.

21. How has approval of a PSP been made faster?

The PIB (20 Jul 2026) lists these steps.

• The CEA cut DPR concurrence time from 90 days to 50 days for all PSPs.
• Inter-State aspects need no clearance for PSPs.
• A Gazette notification of 1 Aug 2025 set the capital-expenditure limit for CEA concurrence of hydro generating station schemes at Rs 3,000 crore.
• Off-stream closed-loop schemes need no CEA concurrence, whatever their cost.
• MoEF&CC notified on 18 May 2023 that PSPs can be appraised in category B2, subject to certain conditions.
• Terms of reference of 14 Aug 2023 set baseline data for one season other than monsoon (closed-loop) or two seasons, pre-monsoon and post-monsoon (open-loop).
• MoP notified tariff-based competitive bidding guidelines for storage on 6 Feb 2025.

22. Is there Viability Gap Funding, an obligation for storage, or a national plan for PSPs?

The PIB (23 Dec 2023) says there are no plans to provide Viability Gap Funding for PSPs. The PIB (23 Dec 2023) says their levelised cost of storage is viable. The Government also gives budgetary support for enabling infrastructure such as roads, ropeways and transmission lines.

The PIB (8 Dec 2022) says the Ministry of Power notified an Energy Storage Obligation trajectory up to 2029-30 on 22 July 2022. The PIB (17 Nov 2025) says Renewable Consumption Obligations for energy storage systems have been notified. The yearly percentages were not found on an official page.

The PIB (9 Mar 2026) says the National Electricity Plan has transmission planned for 35.6 GW of PSPs up to 2031-32. It says transmission is identified for 100 GW of PSPs from 2025-26 to 2035-36.

23. How do the environmental effects of open-loop and closed-loop plants differ?

The Pacific Northwest National Laboratory (PNNL), for the US DOE (April 2020), concludes closed-loop effects are generally lower. They are more localised and shorter in duration. The reasons are that closed-loop plants sit off-stream and often have more siting flexibility.

Aquatic impacts are typically lower for closed-loop plants. They are not continuously connected to a flowing water body. Their main aquatic effect is the initial withdrawal of surface water to fill the reservoir.

But the report says closed-loop plants that use groundwater could have higher impacts on geology, soils and groundwater. All 43 US plants were open-loop then. So closed-loop effects were not well documented.

24. What about water use and evaporation in India?

Reservoirs lose water to evaporation. The PIB (17 Nov 2025) says the Power Minister suggested floating solar on PSP reservoirs as a solution.

The same release says the Consultative Committee noted PSPs’ relatively lower environmental impact. It also quotes the Minister on the role of State Governments in timely site allocation, water allocation and clearances. The MoEF&CC steps in item 21 cover baseline surveys for off-stream sites.

No page checked here gives figures on land take or displaced families for PSPs. So this lesson gives none.

25. What did UPSC ask on pumped-storage hydropower in 2024?

The stem below is from the UPSC question paper, Civil Services (Preliminary) Examination 2024, General Studies Paper I, Set A, Question 38. The text was read from the scanned page.

“Recently, the term “pumped-storage hydropower” is actually and appropriately discussed in the context of which one of the following?”

• (a) Irrigation of terraced crop fields
• (b) Lift irrigation of cereal crops
• (c) Long duration energy storage
• (d) Rainwater harvesting system

Answer: (c), from the PIB line on long-duration energy storage and the DOE line on energy storage. Official key (Series A): (c).

26. Has UPSC asked about related energy topics in the same paper?

Yes. Question 27 of the same paper (Set A) asked about distributed energy resources.

“Consider the following: 1. Battery storage 2. Biomass generators 3. Fuel cells 4. Rooftop solar photovoltaic units. How many of the above are considered “Distributed Energy Resources”?”

• (a) Only one
• (b) Only two
• (c) Only three
• (d) All four

Official key (Series A): (d) All four. Question 37 of the same paper asked about the exhaust of Fuel Cell Electric Vehicles. See the sibling lesson on FCEVs.

The 2025 and 2026 Prelims papers were not scanned for energy storage items.